1. Field of the Invention
The present invention relates to a circuit device and, more specifically, to a circuit device with heat radiation capability and dielectric strength.
2. Description of the Related Art
The configuration of a conventional hybrid integrated circuit device 100 will be described with reference to FIG. 9 (this technology is described for instance in Japanese Patent Application Publication No. Hei05-102645). A conductive pattern 103 is formed on an insulating layer 102 provided on the surface of a rectangular board 101. A circuit element 105 is fixed to the desired portions of the conductive pattern 103 to form a predetermined electric circuit. Here, a semiconductor element and a chip element are connected as circuit elements to the conductive pattern 103. Leads 104 are connected to the conductive pattern 103 formed on the edge of the board 101, and serve as external terminals. Sealing resin 103 serves to encapsulate the electric circuit formed on the surface of the board 101.
The structure of the board 101 is of two types: the first is achieved by forming the sealing resin 103 with the back surface of the board 101 exposed to the outside, thereby releasing heat effectively through the board 101 exposed to the outside; the second is achieved by forming the sealing resin 103 in such a way as to encapsulate the entire board 101 including its back surface, thereby ensuring that the board 101 has a dielectric strength and moisture resistance. In this drawing the entire board 101 is encapsulated, including its back surface. The thickness of the sealing resin 103 that covers the back surface of the board 101 is, for example, about 0.5 mm. The foregoing second structure is particularly employed in a case where the board 101 is connected to the ground potential, and therefore, the board 101 is insulated from the outside.